Careful metabolic monitoring and proper treatment can improve control of metabolic diseases such as diabetes and obesity. Knowing a patient's metabolism along with other physiological parameters allows for correct dosing and delivery of medications and nutrients. Improvements in metabolic measurement technology are essential for better diagnostics and advances in treatment of metabolic diseases and conditions. Treatment of metabolic diseases and conditions ideally requires frequent and timely monitoring which drives a need for monitors that are non-invasive, real-time, portable, low cost, and accurate. Metabolic data are also useful in assessing the physiological homeostatic conditions of patients and healthy subjects in general.
Blood glucose concentration data is extremely useful for the control of metabolic diseases such as diabetes and for monitoring the overall metabolic condition of a human subject. An accurate, real-time, noninvasive method for measurement of blood glucose levels is of great interest in the diabetic community. Current technologies involving the measurement of blood glucose by drawing blood are invasive and often lead to poor patient compliance. Measurement by probe involves frequent lancing and may result in problems. An ideal non-invasive blood glucose sensor provides a continuous signal and/or a signal on demand that can be used to control devices, such as insulin pumps in closed loop feedback applications.
In recent years, two different types of metabolic internal units have been developed: non-invasive and minimally invasive. Non-invasive optical internal units depend on light penetration into the skin and spectroscopic measurement of metabolic levels; however, lack of analyte specificity remains a problem for optical internal units. Commercially available minimally invasive internal units can function only for the short term (a few days) and require frequent calibration via finger pricking. These commercially available internal units are either incapable of continuous monitoring of metabolic levels or are only suitable for use by qualified medical personnel.
Therefore, there exists a need for a minimally invasive or non-invasive metabolic internal unit suitable for use by the host that allows continuous and/or on demand monitoring of metabolic levels of specific analytes.